Radiotransmission



Patented Dec. 31, 1935 UNITED STATES PATENT OFF a 2,026,005

YBA'DIOTRANSMISSIONI George Wald, Mount Clemens, Mich. Application Jam 24, 1933, Serial No. 677,496

5 Claims. '(cl. 25o-2 This invention relates to the art of radio transfrequency mixer and source of potential for the mission and is especially applicable to television. circuit are such as to produce high power low fre- An' object of this invention is to transmit sigquency oscillations which are deformed by the' nal impulses, such as television impulses, on a frequency mixing circuit, that is to say, by the 5 high power low frequency carrier by first modulow power high frequency oscillations which have 5 lating a low power high-frequency by means such already been modulated by the television signal as a television camera circuit and deforming the current. The frequency mixing circuit including low frequency transmission carrier by the high the mixing tube 4 is inductively connected by the frequency waves, receivingthe low frequency cartransformer 6 to an antenna circuit including an 1 rier and reconstructing therefrom the high freantenna 8.

quency carrier from which the transmittedsig- A circuit is inductively connected to the oscilnals may be reproduced. lating circuit including the oscillator and in- With this object obtained a broad wave band eludes the auxiliary secondary 9. A rectifying television current may be accommodated without circuit, including a rectifier I0, is inductively conc in the wid h of the main radio carrier nected to the last named circuit and is supplied 15 wave band. By the use of this invention the by power from the low power auxiliary secondary trouble and uncertainty experienced with the re- 9. The rectifying circuit is connected, as shown ception of high frequency signals is eliminated to the oscillating circuit including the oscillator as is also the trouble due to broad wave bands 3 in such a manner as to stop the oscillations of when the long wave carrier, deformeddirectly the oscillator 3 when the potential on the oscil- 20 57 s a cuit, s dlator circuit 5 is near zero and the potential in The objects of the invention will be further apthe rectifying circuit reaches a predetermined Parent from the following detail e r ption minimum. Achoke coil may be connected in se-= taken in connec ion wi h e a c mpan i g ries withthe rectifier l0, booster source of power drawing, in which: H and the oscillatingcircuitB so as to make the 2 Fig. 1 is a diagram of a curve produced by a power supplied by the rectifier ill of an amplitude long wave high powered radio transmission carnearly equal at all times except when the potenri r ix W a w power i h fr qu ncy curtial in the oscillator circuit 5 is at or near the rent. zero point. On account of the coupling between Fig. 2 is a diagram similar to Fig. l, in which the rectifying and the oscillating circuit 5 the 30 the high frequency intermediate carrier has been power supplied by the rectifier I 0 will be dependmodulated by'television current. ent upon the oscillations of the circuit 5 and thus Fig. 3 is a diagrammatic view of transmission the oscillator 3 will be silenced twice during each circuits embodying this invention. cycle of the oscillator 5, that is whenever the po- Fig. 41s a diagrammatic view of receiving cirtential of the oscillatingcircuit 5 is at or near 35 cults embodying this invention. zero.

A television signal current is produced in the The result of the transmitting station circuit, device I by a means not shown, but which may diagrams of which are. illu trat d in Fig, 3, i be any means responsive to visible signals by shown on the diagrams.Figs. 1 and 2. The lines which an image is scanned and a current pro- I 2, Fig. 1, illustrate the contour of the power 40 du d d p nd nt in ma nitud n th intensity output of the wcillator 3 when its circuit is not of light at the points scanned. The television modulated by the television signal current. The signal current may be amplified by a device 2 even lines l3 illustrate the power output of the the detail of which is not sketched. The amplioscillator 5 without deformation, and the zigzag 45 fying circuit including the amplifier 2 is induclines I 4 illustrate the power output of the modu- 45 tively' coupled to an oscillating circuit including lating circuit 4 when mixed with and deformed an oscllator 3. The oscillator 3 and its circuit by the superimposition of the high frequency low are so constructed as to produce a low power high power oscillations. When the potential, as illusfrequency carrier which will be modulated by the trated by the lines I 3, approaches the zero line inductive coupling with the amplifier circuit. IS the oscillator 3 stops, thus making the power 50 The oscillating circuit is inductively coupled output :of the oscillator 3 zero as indicated by the to a frequency-mixing circuit including the mixstraight lines l2 at IE, IS. ing tubes 4. The frequency mixing circuit is also Fig. 2 is similar to Fig. 1 except that in this L inductively coupled to an oscillating circuit in-' illustration I 2a indicates the power output of the eluding a high power oscillator 5. The circuit, oscillator 8 when its wave is modulated by the While in such a 'to'a high frequency television signal circuit represented by the curve II. The zigzag line Ila represents the carrier wave deformed by the high frequency low power wave as modulated by the television signal current. The shape of the resultant wave H or Ila will depend upon the relative ratio of the superimposed power waves of the oscillators 3 and 5. scheme the television current modulation will be but a very small percentage of the power radiated from the antenna, suchapparent deficiency is taken care of by the use of a local oscillator at the receiver as hereinafter ed. The radiation of power from the antenna 8, as shown by the curve Ila, is received by the antenna ll of the receiver circuit which is tuned to the long wave length of the carrier wave l3,

that is to say, of the oscillations of the circuit 5. The signal is amplified by a tube i8 and applied transformer l9 and the low frequency transformer |9a.1 The primaries of these two transformers i9 and Illa are connected in series with a by-pass condenser across the primary of transformer i9. These two transformers with proper condensers across their secondaries are in such tuned relations as to respond only to desired wave lengths; the transformer l9 responding to the high frequency waves while transformer [9a to the low frequency waves. The by-pass condenser across the primary of transformer l9 acts as an antennae for the high frequency waves causing responsive oscillations in its tuned circuit. In this way the carrier wave is broken into its component parts. A circuit including the secondary of the transformer IS includes an amplifier nected to an oscillating circuit including an oscillator II and a mixing tube 22. The local oscillator 2| is adjusted to oscillate with the same frequency as the oscillator 3, that is, in a. high frequency, as illustrated by the curve I! and is -made to harmonize with the frequency of the incoming signal by the mixing tube "incoming signal. The high frequency oscillations in the local oscillating circuit 2! are further amplified by a tube 23 and are detected by a tube 24. The television current signals, as detected by the tube 24, are applied across the television amplifier 25 and the effective current therefrom is applied to a receiver, not shown, through the circuit. v

In telephone-vision when the time of transmission is divided and part of the carrier is used for sound and the other part for image, the audio signals may be applied to a circuit 1 connected as shown in Fig. 3. The signals thus transmitted by the antenna 8 and received by the antenna I! can be made audible by a circuit Ia connected to the secondary of the transformer 19a (Fig. 4) and the circuit 1a may wave radio circuit and sound reproduced therefrom in a manner well known in the art.

It will be evident that the silencing of the oscillator as indicated at l5 will cause an interruption of the transmission of television signals. This interruption will not cause any lack of fidelity in the received, signals if the rate of scanning is increased over that normally used. Since the number of points scanned will, in the absence of accident, have no relation to the he- 20 and is conductively con- .tively low frequency, means 22. Thus,- the local oscillator current is modulated by the' station, means for be'connected to a long quency of the oscillator 3 the missing impulses will not recur at the same points on the image.

It will be understood that having described the method employed those skilled in theart will at once be able to devise many different circuits 6 forpracticing the method. While some of such circuits have been illustrated and described I do not intend to limit myself to this precise circuit. Parts of the invention may be used withoutthe whole, additions may be made thereto, and various changes may be made in the details of construction, of the apparatus and of the circuits, within the scope of the appended claims, without departing from the spirit of this invention.

I claim:

1. In the art of radio transmission, the method including modulating at a transmission station a low power high frequency carrier by a signal current deforming a relatively high power low frequency carrier by the said modulated high fre- 20 quency carrier, transmitting and receiving the low frequency carrier 'so deformed, reconstructing therefrom at a receiving station high frequency waves corresponding to the modulated high frequency carrier produced at the transmitting station, and reproducing from said high'frequency waves, signals corresponding to those influencing the signal circuit.

2. ma radio transmission set, a signal circuit, an oscillating circuit adapted to oscillate at a 30 relatively high frequency, means for'modulating the oscillating circuit by the signal circuit, means for producing a, relatively high power low frequency carrier, and means for deforming said carrier by said high frequency circuit.

3. In a radio transmission set, a signal circuit, an oscillating circuit adapted to oscillate at a relatively high frequency, means for modulating the oscillating circuit by the signal circuit, an oscillating circuit adapted to oscillate at a relafor deforming the wave produced by the low frequency current by said high frequency current by superimposition, and means for choking the high frequency circuit when the potential in the low frequency circuit is at and near zero.

4. In radio apparatus, a signal circuit, an oscillating circuit adapted to oscillate at a relatively high frequency, means formodulating the oscillating circuit at the signal circuit, means for producing a relatively high power low frequency carrier, and means for deforming the carrier by said high frequency circuit, all at a transmitting transmitting and receiving such deformed low frequency carrier, means for 55 reconstructing at a receiving station a high frequency current corresponding to the modulated high frequency current at a transmitting station, and means responsive to said high frequency current for reproducing signals.

5. In a receiving set adapted to receive a relatively high power low frequency carrier deformed by a relatively low power high frequency current, a receiving circuit tuned to such low frequency, an oscillating circuit tuned to such high frequency and including a power oscillator, means for influencing said oscillating circuit by the receiving circuit, and a signal circuit responsive to said oscillating circuit.

GEORGE WALD. 

